Balloon angioplasty is utilized as an alternative to bypass surgery for treatment early in the development of stenosis or occlusion of blood vessels due to the abnormal build-up of plaque on the endothelial wall of a blood vessel. Angioplasty typically involves guiding a catheter that is usually fitted with a balloon through an artery to the region of stenosis or occlusion, followed by brief inflation of the balloon to push the obstructing intravascular material or plaque against the endothelial wall of the vessel, thereby compressing and/or breaking apart the plaque and reestablishing blood flow. In some cases, particularly where a blood vessel may be perceived to be weakened, a stent can be deployed following an angioplasty procedure to support the vessel.
Balloon angioplasty and stent deployment, however, can result in injury to a wall of a blood vessel and its endothelial lining. For example, undesirable results such as denudation (removal) of the endothelial cell layer in the region of the angioplasty, dissection of part of the inner vessel wall from the remainder of the vessel wall with the accompanying occlusion of the vessel, or rupture of the tunica intima layer of the vessel may occur. A functioning endothelial reduces or mitigates thrombogenicity, inflammatory response, and neointimal proliferation.
To reduce or treat injury to the vessel wall, angioplasty balloons and stents may further be used to deliver treatment agents to the targeted vessel regions. The use of angioplastly balloons and stents to deliver treatment agents, however, may be limited by the type of drug being delivered. In addition, stents can undesirably increase the profile and stiffness of a delivery system, affect drug distribution and require a high-pressure angioplasty balloon for deployment.